三相電加熱管

        380伏(fu)三(san)相(xiang)四線(xian)(xian)(xian)電(dian)(dian)路中(zhong)，任意兩(liang)根火線(xian)(xian)(xian)之(zhi)間的(de)電(dian)(dian)壓都是380伏(fu)，任意一根火線(xian)(xian)(xian)與零線(xian)(xian)(xian)之(zhi)間都可以組成220伏(fu)。這個系(xi)統可以形(xing)成三(san)種(zhong)(zhong)電(dian)(dian)源(yuan)：即(ji)單(dan)相(xiang)220伏(fu)電(dian)(dian)源(yuan)，單(dan)相(xiang)380伏(fu)電(dian)(dian)源(yuan)，三(san)相(xiang)380伏(fu)電(dian)(dian)源(yuan)，第 I 種(zhong)(zhong)家(jia)用(yong)(yong)比(bi)較多(duo)，第三(san)種(zhong)(zhong)工廠里(li)電(dian)(dian)機類(lei)用(yong)(yong)得(de)多(duo)，第二種(zhong)(zhong)用(yong)(yong)得(de)少，只有(you)交流電(dian)(dian)焊機經(jing)常用(yong)(yong)到單(dan)相(xiang)380伏(fu)電(dian)(dian)源(yuan)。